Where sits the gland packing

[Vronsky]

Dear All,

Here's a picture of the prop shaft seal on my Myra 21, it's leaking.

I intended to replace it with a Volvo Seal, the prop shaft is 25mm but the stern tube measures 43-44mm, so that doesn't fit

Maybe I should first try replacing the gland and see if the leak stops.

Could anyone point me where the gland(s?) in the deal exactly sits ?

 

That little grease container is not working anymore (it doesn't press grease into seal, propably the spring is soft): can these be replaced ?

 

MANY THANKS,

V.

 

 

 

[index]

The gland is to the right. Loosen the left locking nut (next to the grease container), and tighten the gland maybe half a turn. The seal is supposed to leak a few drops per minute when in use, so don't tighten the gland too much.

 

What do you mean with that the grease is not working anymore? There is no spring in here, you just turn the cap to press in more grease. Not too much, and not too often. Half a turn every second month or so is more than enough. Too much will just result in poor water circulation for cooling of the seal and shaft.

 

I can not see any good reason to replace this with a Volvo seal. This is a well proven design that can be used for many years still.

[Rolf]

Agree to the above.

So unscrew the greasecontainer, fill it up with grease and the fasten it again with say 2-3 turns. Then, when in need, another half a turn.

[Vronsky]

THANKS!

Tried turning the container (gently), but it won't move left or right.

Also tried adding grease to the container via the nipple with a grease gun, but I don't notice any effect: seems as if grease can be added forever.

Since adding prop shaft grease, I notice grease coming out around the shaft

Seal doesn't heat up: gets a bit warmish only

[index]

The grease nipple is not supposed to be there, it is just some strange idea from a previous owner. If the grease comes out round the shaft, you have added too much of it! A grease gun gives way too much pressure, the only thing you achieve is to fill the stern tube with grease and prevent the water from cooling the assembly.

 

Turn the cover to the left, it is well greased and should come off easily. If not the previous owner that attached the grease nipple to it has done something strange here as well..

[Vronsky]

Could the grease (also) come around the shaft out because the gland(s?) inside are worn/obsolete?

 

Many thanks for your respons.

 

V,.

Redigert 13.November.2015 av Vronsky (see edit history)

[index]

Not really, the glands are not able to withstand the pressure from the grease gun even if they are fully OK. How much does the seal leak? 4-5 drops per minute when the motor is engaged is correct, if it is more than this you can try to tighten it a bit. But not much, sometimes a quarter of at turn is enough. If it doesn't drip at all afterwards, you have tightened too much...

[Vronsky]

Hi 'index'

Many thank for your replies.

I'm gonna try tightening the nut a bit this weekend, and also try to detach the grease reservoir: hope it doesn't break of and create a leak that sinks 'my precious' ... 

 

The dripping after the last "shot" of grease with the grease gun -incl. grease escaping around the shaft- is actually  VERY little

But the problem is: I just don't like dripping seals and smudgy bilges... 

 

However, I now learned that the existing seal is not so terrible at all.

So what's your opinion on these solutions ?

http://www.westmarine.com/buy/western-pacific-trading--drip-less-moldable-packing--362931

 

THANKS,

V.

[index]

The bilge is a wet and dirty place! Get used to it like the rest of us, or buy a Volvo seal. Personally, I prefer the kind of seal thst you have. I have had this sort for over 15 years now, and they are reliable and easy to maintain. I dont't see a little water and grease in the bilge as a problem, I am not going to use the space for storing anything anyway. But it is your choice, how much effort you want to put into making a hidden space cleaner...

[boble65]

Just set a litle box under were it leaks and empty it after every trip and problems solved ? cheap and effectiv ?

[Hulda]

OK, a bit education:

Stuffing boxe is an old technology. Older than propeller shafts in boats. But the priciple is the same. It is a box filled with something i order to prevent a moving shaft from leaking. Basically this:

 

 

Here we have a rotating shaft, like yours, and inside the box is what we call a 'soft packing'. This packing is meant to leak a couple of drops (water) a minute when rotating. Sationary, no leak. When leaking, you can tighten the nut, thus applying a soft packing pressure on the shaft. What is brown and green are stationary parts. It don't look much like Your system, but this one does:

 

No, here you hav Your nut, lying on the desk supporting the stuffing box. So the packing goes inside the nut and acts like a seal. If you look inside the stuffing box bore, you will see a bearing metall called babbit. And on top of the stuffing box you will se the maual lubricator for the babbit. So the grease is not for sealing the shaft. It is for lubricating the babbit. Lot of people don't get this fact. And concequently overlubricates to stop the leak. Sealing of the shaft and greasing are in fact two separate issues.

 

Further questions, pls. feel free to contact. Before I retired, I was handsomly paid to educate these basic priciples. Now it cost nothing. Sad ;-)

Redigert 14.November.2015 av Hulda (see edit history)

[Vronsky]

Hi Hulda,

The seal on my prop shaft doesn't have the flange: it goes into the rubber hose that stretches over the stern tube

Do you think it still has the babbit bearing ? Otherwise: what would be the purpose of the grease container...?

Does the grease container indeed come off by turning anti-clockwise ?

 

What kind of wrench is best to tighten/adjust both stuffing box nuts (these measure 44mm on mine)

Space is very tight, was thinking using two of these thin ball head wrenches used on bicycles.

 

Cheers,

V.

Redigert 15.November.2015 av Vronsky (see edit history)

[Hulda]

By principle the same. You have a babbit bearing to support gland packing. Or else it would not work (for at very long time). Buy a couple of cheap wrenches and chop them off to suitable length.

 

Grease container should come off as you describe.

[Vronsky]

Tightened the nut 2 turns, leakage is now a bit less, but waterdrops keep coming out a 3-4 per 10 seconds.

Also, grease is stil being squeezed out.

Boat's on the dry now, intend to take it all apart, and renew the packing: how may 'rings' can I expect ?

 

Thanks,

V.

[Hulda]

3

[Vronsky]

I've decided to install a rubber seal, and I'm now removing the old gland.

I want to slide the stuffing box off the prop shaft, but the box gets stuck near the end where it's mounted to the engine.

I notice a few tiny dents and scratches in the shaft, and it seems these bog down the box.

 

Any advise ?

Is the box made of bronze ?

How about drilling a line of holes, or grinding/milling a line perpendicular to the thread, so the box will release its clamp ?

 

[Vronsky]

[uPDATE]

FYI: 

used sandpaper to polish the shaft, and the gland come off right away.

New seal went on smoothly >>

 

 

Noticed the prop shaft enters the sterntube a little askew: seems the alignment is not optimal >>

 

 

Best Regards,

V.